There are three basic was to connect your HDTV MythTV box to your HDTV. HDTV is a high resolution digital signal. S-Video is not able to handle the high resolution signal for example. The suggested connections types are:
The decision of how to hook this up has a lot to do with which connections your HDTV screen supports. If your HDTV display doesn't support one (or some) of the above connections, then you have less options.
The worst quality way to hook MythTV to your HDTV is using a standard VGA cable. While many displays will support this, it's not the way to go if you have a better option. This is because VGA is an analog signal. The HDTV signal starts out life in MythTV as a digital signal. It is then converted into an analog signal and send down the VGA cable. When the signal reaches the HD display, it's converted back into a digital signal for display. This conversion process introduces loss in the quality of the resulting picture. It's best to have digital all the way through.
DVI is the standard in the computer industry for connecting computers to digital LCD screens. Because the signal is digital 1 to 1 pixel mapping all the way through, there is no loss.
HDMI is the industry standard for hooking digital entertainment devices like HD-DVD players to HDTV displays. HDMI looks somewhat similar to a USB connector. HDMI can combine audo and video on the same cable, although for most MythTV uses, it will only carry video. The video porting of the HDMI signal is actually a DVI connection with a different connector on the end. That means it's simple and inexpensive to manufacture and buy cables that convert a DVI signal to HDMI since it's just a matter of have a cable with both ends and the proper wire connections. DVI to HDMI cables or connectors are probably the best way to go from your MythTV box to a HDMI input.
Actually, HDMI comes in two variants, A and B. Type B is basically the same except it can carry two DVI signals at once, which should not be required for most (all?) current MythTV setups.
HDMI is the way to go if your HDTV display supports it, with DVI a close second, if only for connector size reasons. Chances are your HD display support one of those two connector types.
One word on cables, as long as you are going short lengths, the quality (and price!) of the cable does not matter much with digital. Because a signal is either on or off (1 or 0), slight signal drop-off and interference does not affect the resulting picture in most situations. In most cases, a 6ft cable you buy for $15 will have the same picture quality as a $100 one, which was not so true for their analog cousins.
So in summary, go with HDMI or DVI if you can, and if you do, don't go overboard on cables.
